Since late January, 2018, I had been having trouble with the "activity" in my gut; things weren't processing in due time, and bowel movements were somewhat painful and strained.  My doctor treated me for diverticulitis and requested that I take the Cologuard cancer screening test.  Usual cancer screening involves checking the stool for signs of blood, but Cologuard (a fairly recent development) went further than just checking for blood.  The test required sending to the lab a full stool sample that was to be "deposited" in a plastic container (provided); the sample is then sent to the laboratory through the mail.  The results indicated that while there was no blood in my stool, there was an indication of the presence of abnormal DNA.  

My doctor insisted that I get a colonoscopy ASAP.  

I hate colonoscopies (who doesn't?).  The idea of having my colon pumped up with gas and having a camera (Nikon?) slithered up my butt was just not appealing.  At the same time, the results of the Cologuard test were a bit scary so ... I called up my GI doctor and was scheduled to have the procedure done on April 13, 2018 - the soonest date the doctor could fit me in (or fit in me, as the case may be).  That particular date fell on a Friday - Friday the 13th! - and I joked about how it was just my luck - they'd probably discover that I had cancer or something.  

Sure enough, the doctor found a tumor in my descending colon, apparently close to the sigmoid colon (didn't have to shove the camera too far up). Normally, my GI is a happy-go-lucky, cheerful, guy who give a happy pep talk as he shows you the pictures of your colon and tells you how healthy you are; this time he was straight faced and serious as he showed me the picture of a donut-like ring in my colon. It looked to be a serious tumor, and he rushed me to the local hospital for a CT scan (that very same day).  

The scan confirmed the presence of a donut-shaped tumor in my descending colon.

Aha!  The joke was on me.

An appointment was set up with the colorectal surgeon my GI usually referred his patients to.